This invention relates generally to small-lot bookbinding techniques, and in particular to a technique in which a stack of collated paper sheets to be bound is inserted within a folder and adhered to the backbone thereof.
Binding machines of the type used to mass-produce books are highly complex and expensive and therefore unsuitable for small-lot binding operations. In order, therefore, to make it possible to bind legal briefs, technical reports and other multiple-page documents in relatively small lots, various bookbinding schemes have been devised for use by office personnel rather than by professional binders. The term small-lot, as used herein, refers to a production run not usually in excess of 100 copies and often well below this number.
In one known small-lot bookbinding arrangement which is commercially available, the stack of collated sheets to be bound is sandwiched between cover sheets to form an assembly, and the sheets are then in sub-sets sequentially fed into a mechanical puncher adapted to punch edge holes therein. Thereafter a plastic spine is applied to the punched sheets, the spine being provided with complementary rows of curved teeth which enter the holes to bind the assembly. The operations involved in this binding technique require a fair degree of skill and are time-consuming, for the operator must exercise care in punching the holes and use a special device to apply the spine.
In another known technique for small-lot binding as disclosed in U.S. Pat. No. 3,321,786, use is made of a device adapted to clamp a stack of sheets so that the edge thereof may have liquid adhesive applied thereto by an operator. This process is slow and inefficient and is generally unsuitable for office personnel. In an attempt to improve this technique, U.S. Pat. No. 3,757,736 provides a machine which clamps the pages to be bound on a carriage that travels across a rotating drum serving to apply a hot melt glue to the exposed edge of the clamped pages. But this machine requires operating skills and the preparation of a heated liquid adhesive.
In order to simplify small-lot binding operations, U.S. Pat. No. 3,717,366 shows an arrangement in which a paper stack is inserted within a folder and is adhered thereto by means of a solid strip of hot-melt adhesive that must be interposed between the edge of the stack and the back of the folder, heat then being applied to melt the adhesive to bond the edge of the stack to the back of the folder.
One difficulty with this known arrangement is that the thickness of the stack varies from lot to lot, hence the adhesive strip must in each instance be tailored to conform to the changing thickness requirements. Moreover, since the width of the inserted strip can be no greater than the width of the back, in practice this adhesive may fail to bond the top and bottom sheets in the stack, which remain loose and unbound, the resultant book being unacceptable.